Method and apparatus for storage of gaseous substances in an underground aquifer



May 10, 1966 P. A. wlTHERsPooN 3.250.326

METHOD AND APPARATUS FOR STORAGE OF GASEOUS SUBSTANCES IN AN UNDERGROUND AQUFER Filed July 29, 1965 6 Sheets-Sheet l f 24 25 l V V Z@ 22 V 5^ /8 MMM/6%@ May 10, 1966 P. A. wlTHx-:RsPooN 3.250.326

METHOD AND APPARATUS FOR STORAGE OF GASEOUS SUBSTANCES v IN AN UNDERGROUND AQUIFER Flled July 29, 1963 6 Sheets-Sheet 2 May 10, 1966 P. A. wlTHERsPooN 3,250,326

METHOD AND APPARATUS FOR STORAGE OF GASEOUS SUBSTANCES IN AN UNDERGROUND AQUIFER Filed July 29, 1963 6 Sheets-Sheet 5 May 10, 1966 P. A. wlTHERsPooN 3,250,326

METHOD AND APPARATUS FOR STORAGE OF GASEOUS SUBSTANCES IN AN UNDERGROUND AQUIFER Filed July 29, 1963 6 Sheets-Sheet 4 INVENTOR' ,DAUL AW/T/-IE/QSDOOA/ May 10, 1966 P. A. WITHERsPooN 3,250,326

METHOD AND APPARATUS FOR STORAGE OF GASEOUS SUBSTANCES IN AN UNDERGROUND AQUIFER Filed July 29, 1963 6 Sheets-Sheet 5 INVENTOR.

' pdf/L A. VV/ mg/ZQDOO/U 'l May 10, 1966 P. A. wlTHERsPooN METHOD AND APPARATUS FOR STORAGE OF GASEOUS SUBSTANCES IN AN UNDERGROUND AQUIFER 6 Sheets-Sheet 6 Filed July 29, 1963 INVENTOR,

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,d70/PNE Y@ United States Patent O 3,250,326 METHOD AND APPARATUS FOR STORAGE F GASEOUS SUBSTAN CES IN AN UNDERGROUND AQUIFER Paul A. Witherspoon, Berkeley, Calif., assiguor to Panhandle Eastern Pipe Line Company, Kansas City, Mo., a corporation of Delaware Filed July 29, 1963, Ser. No. 298,146 16 Claims. (Cl. 166--4) This invention relates to the storing of gaseous substances, for example natural gas, in underground stratum, and more particularly to a method and apparatus for the storing of gaseous substances in an underground aquifer or water-bearing strata wherein gas is injected in the aquier to for ma gas-containing space therein.

Natural gas is used for heating and other purposes in locations remote from sources thereof, and it is common practice to transport the gas from such sources to regions of use by means of pipe lines. The demand for gas varies throughout the year and in the wintertime the demand is a number of times that of the summertime. While it is desirable for the pipe lines, from the standpoint of sound economics, to 'be operated substantially at full capacity of the line, it is prohibitively expensive to provide a pipe line of a capacity sufficient to satisfy periodic peak demand and then operate the facilities at a small percent of the capacity during the marjor portion of the year. Therefore, the economic utilization of gas at points remote from its source requires storage facilities to be provided so that during periods of off-peak load the gas can be stored so that it is available to supplement the supply of gas available from the pipe line during periods of higher demand, and also to provide a supply available to the consumer in the event of an interruption in the supply upstream in the pipe line. In favorable locations, it has been found possible to pump gas into exhausted gas wells during periods of off-peak load, and to make this compressed gas from the well available during periods of heavy load. However, it is desirable to have the storage near the point of consumption and in most instances such exhausted gas wells are not available in those areas. Also, there has been some storage in underground cavities wherein a cavity is formed by mining or by dissolving soluble salt from a stratum wherein the stratum in which the cavity is formed either has the property of low permeability, that is high resistance to gas migration, or the interior of -the cavity is sealed in some manner. Such cavity forming is expensive and the available locations are limited and do not oifer a solution to the problem Where the gas is consumed in regions remote from old gas fields or from soluble subterranean salt deposits.

In accordance with the present invention, it is proposed to locate suitable underground aquifers, that is, a water- .bearing stratum wherein the natural formation has a porosity of from percent or above, preferably having a porosity of 10 to 30 percent, with the stratum thereabove of low permeability, that is, high resistance to gas migration, the stratum above the aquifer being referred to as caprock preferably having la permeability of 0.001 millidarcy or below. The equifer preferably should occur at a suicient depth below the surface to permit relatively high storage pressure without leakage therefrom. The aquifer may have a source of underground water supply and, therefore, be what may be called a water drive reservoir. It is proposed to provide and complete a well to the aquifer with a ow passage communicating with the upper portion of the aquifer and a separate flow passage communicating with the lower portion of the aquifer with pressure flow equipment to inject gas in the upper part of the aquifer and simultaneously remove water from the lower portion of the same aquifer to form a gas bubble ice or storage space therein. It is further proposed that after the gas storage has -been provided that gas can be injected or produced at the top part of the aquifer and simultaneously water can be produced or injected at the bottom part of the same aquifer.

Another application of the invention is to locate the gas-water interface adjacent the well and vary the rate of injection or production of gas and the rate of production or injection of water to form a down-cone in the water adjacent the well for increased gas volume adjacent the well and also optimum production rates.

The principal objects of the present invention are to provide a method and apparatus for utilizing underground aquifers for gas storage; to provide such a method and apparatus for injecting or producing gas and simultaneously producing or injecting water to control the gas-water interface adjacent the well; to provide such a method and apparatus wherein the permeability of the aquifer and its resistance to water movement therethrough and a caprock of low permeability cooperate to confine the stored gas; to provide for montoring the gas-water interface and regulating the flow of gas and water through the passages leading to the aquifer to maintain a downcone of the gaswater interface adjacent the well; and to provide a gas storage that is efiicient, capable of large capacity at relatively high pressures and that does not affect the surrounding countryside in appearance or utility.

Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth by way of illustration and example certain embodiments of this invention.

FIG. l is a diagrammatic view in elevation and partial section through a gas storage system embodying the features ofthe present invention as the gas is lbeing introduced and water removed from the aquifer to start the gas storage therein.

FIG. 2 is a similar diagrammatic view of the gas storage system wherein the gas-water interface in the aquiiier has a down-cone adjacent the well.

FIG. 3 is a diagrammatic view of a gas storage system with a modified form of apparatus for operating same.

FIG. 4 is a diagrammatic view of a modified form of sub-surface equipment in a gas storage system.

FIG. 5 is a diagrammatic view of a further modified form of sub-surface equipment.

FIG. 6 is a diagrammatic view of a gas storage system wherein different wells are used for the gas and water injection and withdrawal.

It is desired that the gas storage be located near the gas distribution area in the territory to be serviced by a natural gasl pipe line. Starting with known geological data and known methods and procedures for exploring and logging sub-surface strata, suiiiciently full information of such strata or formations is obtained. The site should contain a thick aquifer stratum preferably having a porosity of l0 to 30 percent with a thick caprock thereover having a permeability of 0.001 millidarcy or below. Also, the aquifer should be at a suicient depth, as for example, at five hundred feet below the surface with the water therein at relatively high pressure so as to permit such pressure for gas stored therein. Known techniques for exploring and logging sub-surface formations are utilized and the drilling of bore holes is accomplished in such fashion as to enable cores to be obtained whereby study enables the physical characteristics of the aquifer and the rock formations overlying the storage aquifer to be determined. The drill holes also furnish information as to existence of underground water conditions, both above and below the storage horizon, and known electrical and radio-active logging techniques of the bore holes will furnish additional information as to primary and secondary permeability features of the sub-surface rock, all in accordance with known procedures.

With the foregoing information in mind, the desired location of the well is determined and then a bore hole 1 is drilled from the surface 2 downwardly through the cap- .rock 3 and through the aquifer stratum 4 in accordance with known drilling procedures. It is preferred that the bore hole 1 extend to the underlying rock o-r straum 5 below the aquifer 4, or to a sufficient depth if the aquifer stratum 4 is excessively thick, and be closed as at 6 adjacent thereto. A casing 7 is introduced into the bore hole 1 and moved downwardly until the lower end is at the closed end 6 of the bore hole and then said bore hole is provided with a barrier 8, as for example cement, along a sufficient length in accordance with known procedures to form a complete barrier, preventing any passage of uid upwardly in the bore hole 1 around the exterior of the casing 7. In the structure illustrated in FIGS. l to 3 inclusive, the bore hole 1 extends a substantial depth in the aquifer and the cement surrounds the portion of the casing 7 therein supporting the formation and the apertures 18 and 19 extend through the casing and cement. The upper end `of the casing is provided with a casing head 9 through which a tubing or small-er diameter inner casing 10 extends downwardly in the casing 7 in spaced relation to the walls 11 thereof and cooperating therewith .to define an annulus 12 between the tubing and casing.

The tubing 10 extends into the lower portion of the yaquifer and, if desired, may extend to adjacent the closed end 6 of the bore hole, said tubing forming a flow passage 13 therein having a bottom inlet 14 communicating with the lower portion of the aquifer. In the structure illustrated, a suitable packer or other sealing device 15 is arranged in the casing surrounding the tubing intermediate the height of the aquifer stratum 4 to form a complete barrier defining a lower zone 16 and an upper zone 17 in the casing, said lower zone having communication with the lower portion of the aquifer through a plurality of apertures 18 whereby water from the lower portion of the aquifer can freely flow into the lower zone 16. The annulus 12 in the casing forms a flow passage t-o the upper zone 17 above the packer 15 and has communication with the upper portion of the aquifer 4 through a plurality of apertures 19 around the casing adjacent to and below the lower face 20 of the caprock 3, the apertures 19 being of suffi-cient quantity and size to permit suitable ow of gas therethrough.

A conduit 21 is attached to the casing head 9 for flow of gas to and from the annulus 12 between the casing 7 and the tubing 10. A conduit 22 is attached to the tubing 10 and provides for introduction or removal of water from the ow passage or bore 13 in the tubing. The gas may be introduced under pressure by any suitable means and, in the illustrated structure, a pipe line 23 in which gas is moved from a source to a distribution area has a iiow connection 24 to the conduit 21. It is preferred that a compressor 25 be in the connection 24 and that valves 26, 27 and 28 be arranged for control of the gas so that when desired, as for example during low peak demand, the valves 26, 27 and 28 may be opened and the comp-ressor 25 operated to move high pressure gas from the pipe line 23l and deliver said gas at required pressure through the conduit 21, annulus 12 and apertures 19 to the upper portion of the aquifer 4. In the illustration, a distribution line 29 has a connection 30 having a valve 30' therein, with the pipe line 23, and also a connection 31 having a valve 31 therein, with the connection 24 between the valves 27 and 28 whereby the distribution pipe 29 may be served either from the pipe line 23 or from the storage. There is also a connection 32 having a valve 32 therein from the connection 24 to the pipe line 23 between the valves 27 and 28 for flow from the conduit 21 back to the pipe line 23, if desired.

`It is to be understood that these connections between the pipe line and the distribution line 29 and the conduit 21 are merely an example and may be varied in conventional manners to accommodate variations in gas transmission and distribution procedures.

A suitable water lift is connected to or installed within the tubing 10` to move water from the lower portion of the aquifer 4. Such a pump or lift may be any known lift of substantial capacity, as for example a mechanical pump such as a submersible electrically d-riven pump installed at the lower end of the tubing, or a gas injection system utilizing gas from the annulus 12. In the structure illustrated in FIG. 1, a pump 33 such as an electrically driven submersible pump is mounted on the lower end of the tubing 10 below the packer 15 to pump water from the lower portion of the aquifer 4 upwardly through the tubing 10 to discharge the water through the conduit 22 to a water reservoir 34 with excess water being suitably disposed. It is to be understood that with tubing 10 of suitable size, the pump 33 may be installed within the tubing 10 on its own individual smaller sized tubing, thus permitting the withdrawal of the pump 33 without necessitating the removal of the tubing 10. A pump 35 having an inlet connected to the reservoir 34 is als-o connected by a pipe 36v to the conduit 22 for pumping water from the reservoir back down through the tubing 10 to the lower portion of the aquifer to return water thereto when desired. Suitable valves 37 and 33 are arranged in the conduit 22 and the pipe 36 and are operated to permit water movement therethrough.

In the structure illustrated in FIG. 3, a gas lift for the water is provided, gas under pressure being delivered from the connection 24 through a valved conduit 40 to a plurality of gas injection nozzles 41 of conventional gas lift type spaced along the length of the tubing 10 whereby the gas will lift the water upwardly in the tubing and with such a system the conduit 22 is connected to a separator 42 to separate the gas from the water, the separated water going to the reservoir 34 and the gas from the separator being discharged through a conduit 43 to a point of use. It is to be understood that, if desired, the conduit 40 and injection nozzles 41 could be connected to the tubing 14D in such a way that the conduit 40 would extend downward solely within the tubing 10 to the depth desired for nozzles 41, thus permitting the Withdrawal of the conduit 40 without necessitating the removal of the tubing 10.

In the system with any form of Water lift, it is preferred that the upper end 44 of the tubing 10 be closed by a valve 45 and be arranged whereby a suitable logging instrument 46 may be extended downwardly inside of the tubing 10 to determine the gas-water interface 47 at or adjacent the casing, as for example, a conventional neutron logging instrument may be inserted at any time and moved up and down to locate the interface. It is to -be understood that any suitable level indicator may be incorporated in the structure to provide an indication of the upper surface of the water in the aquifer 4 at the casing 7 or, in other words, the gas-Water interface 47 adjacent to and immediately surrounding the casing 7.

To store gas in the aquifer 4, the valves 26, 27 and 28 are opened, the compressor 25 operated to draw gas from the pipe line 23, with said gas passing through the compressor which discharges same at a suitable pressure through the conduit 21, annulus 12, apertures 19, into the upper portion of the aquifer 4. The pump 33 is operated to pump water from the lower portion of the aquifer up through the tubing 10, conduit 22, to the reservoir 34, the pump 33 removing the water of which part or all would be displaced by the volume of gas injected into the upper portion of the aquifer. The water level or gas-water interface 47 adjacent the casing 7 and the known properties of the aquifer are considered to arrive at a gas injection iow rate wherein the gas-water interface remains substantially horizontal within the aquifer 4 and outside the casing 7. rThen to increase the effective thickness of the gas storage zone, water is produced from the lower part of the aquifer through the apertures 18 at a higher rate than any water flowing in the formation toward the casing so that the gas pressure and the water removal rate forces the water down adjacent the casing to effect a conical depression in the gas-water contact or interface as is shown at 48 (FIG. 2). This down-cone increases the volume of gas storage adjacent the casing whereby the gas is more readily available for production due to its proximity to the casing, and thereby the short distance that it must move through the aquifer strata. The rate of the water removal is then varied to maintain the desired down-cone, the lower extremity of which is located by the interface indicator 46. This assures that no gas will be removed by the pump 33, as said lower extremity of the interface at the down-cone will always be maintained above the apertures 18 through which the water flows to the pump 33.

When sufficient gas is stored or the demand for the gas in the pipe line 23 increases whereby no more gas for storage is available, the compressor 25 is shut down and the valves 26 and 27 are shut olf. However, the pump 33 may continue to be operated when necessary to substantially maintain the down-cone in the gas storage of the aquifer 4. In high peak demand on the gas from the pipe line 23, the valved connection 32 may be opened whereby the gas pressure in the storage gas zone of the aquifer flows through the apertures 19 upwardly in the annulus 12 through the conduit 21 and connection 32 to the pipe line 23, or if the demand is in the distribution line 29 the valved connection 32 would remain closed and the valved connection 31 opened whereby the gas flow would be to the distribution line 29 for use in the system. The valve 28 would be regulated to govern the rate of flow and, if the rate of ilow were such that there would be a pressure drop, the pump 33 could be shut down, and if there were a further pressure drop the pump 35 would be actuated to withdraw water from the reservoir 34 and pump same down the tubing to inject said water into the lower portion of the aquifer. It is to be understood that the pump 33 should be of such design as to permit flow of water in the tubing in either direction.

While I have illustrated only one well in FIGS. 1 to 3 inclusive, it is to 'be understood that in large areas more than one well could extend to the same aquifer, the wells being spaced whereby the storage reservoir or doWn-coned bubble of the gas for each well may be kept separated by the water or may coalesce to varying degrees depending upon the aquifer properties, spacing between walls, and by the control of the water and the gas rates of injection and production. Control of the gas and water flow rates to and from the aquifer provides a controlled volume of gas storage defined by the gas-water interface 47 and the surface 20 of the caprock 3.

In operating of such a gas storage, it s desirable to always maintain a quantity of gas in the aquifer 4 to form a minimum storage volume. This minimum gas storage may be called cushion gas. However, by operating the storage to maintaing the down-cone adjacent the well, provides economical operation with less cushion gas required and a larger percent of the gas storage available for use. It such operation, the gas pressure can be controlled whereby it is some desired differential pressure either above or below or substantially the same as the native pressure provided by -the water in the aquifer 4 in order to control the gas storage volume or bubble and maintain water in the lower portion of the aquifer adjacent the casing 7. The aquifer may be of a type wherein the stratum is of the water-drive type having a water source or may be of a type wherein there is little or no water production, and the water removal or injection effected by the pumps 33 and 35 respectively may be adjusted accordingly.

The form of the invention illustrated in FIG. 4 differs only in the sub-surface equipment. The outer casing 50 is provided with a special landing nipple 51 that reduces the hole size to that of a suitable size casing 52 that can be inserted within the outer casing with the walls of said casings spaced providing an annulus 53 therebetween. The landing nipple 51 provides a shoulder 54 and a casing shoe 55 on the lower end of the inner casing 52 seats -on said shoulder, the annulus 53 extending upwardly from said shoe 55. The water withdrawal equipment is then inserted within this inner or smaller casing 52 and the water withdrawal accomplished with conventional tubing and a suitable pump. It is preferred that the inner casing 52 have a hardened outer surface 56 in t-he area at the apertures 19 and extending above and below same to resist any wear that may tend to be caused by passage of substances thereby. The surface equipment substantially corresponds to that shown in FIG. 1, and the operation is substantially the same with the gas moving to and from the storage through the annulus 53.

In the form of the invention illustrated in FIG. 5, an outer casing string 7 is set completely through the caprock and aquifer. A smaller size string `of casing 57 is then run inside `of the casing 7 to provide an annular space 58 therebetween with the lower end of said space 58 sealed olf by means of a suitable packer 59 below the apertures 19. Water withdrawal equipment is then installed within the inner casing 57 and the system `operated substatntially in the same manner as described in the system illustrated in FIGS. l to 3 inclusive.

In the form lof the invention illustrated in FIG. 6, separate well holes `60 and 60 are drilled into the aquifer 61. The Well hole 60 is equipped only for gas injection and withdrawal and the well hole 60" is equipped only for water withdrawal. The distance between the two well holes is minimized so the maximum benefit can be derived around the gas injection-withdrawal well from a down-coned accumulation of gas that is produced at the water withdrawal well. The well hole 60 has only a casing y62 set therein and closed at the bottom. A barrier 63 such as cement closes the bore hole around the casing above the aquifer and preferably encloses the casing in the aquifer to support the information. Apertures 64 communicate the bore of the casing 62 with the aquifer adjacent the upper portion thereof. The upper end of the casing bore is connected to a conduit for movement of gas into and out of the aquifer in the same manner as described relative to the movement of gas through the annulus 12 in the form of the invention 4illustrated in FIG. 1. The well hole 60' has a casing 65 substantially corresponding to the casing 7 of FIG. l except the apertures 19 are omitted and there is no gas connection at the upper end. The tubing 10 and pump 33 are inserted and supported in the casing and connected to surface equipment substantially as described relative to the equipment shown in FIG. l and operated in the same manner to cause a down-cone for gas in the aquifer around the casing 62.

It is to be understood my invention is not limited to the particular types of well completion shown in the accompanying drawings which are for the purposes of illustration only. My invention may employ other completion methods and variations in the apparatus and operation thereof whereby the gas and water are segregated in the aquifer and are moved to and from the surface by any combination of separate flow channels utilizing one or more strings of tubing, either parallel or concentric, or the annulus with the tubing. It is also to be understood that the production or withdrawal of water and injection of gas need not be literally simultaneous but may be periodic over short time intervals during which time interval there is not substantial movement of the gas-water interface. The term simultaneous as used in the appended claims is meant to include such periodic operations.

It is to be understood that while l have illustrated and described certain forms of my invention, it is not to be limited to the specific forms or arrangement of parts herein described and shown, except insofar as such limitations are included in the claims.

What I claim and desire to secure by Letters Patent is:

1. The method for producing an underground storage space for gaseous substances under high pressure comprising, exploring a desired area by known geological procedure, including the formation of a bore hole to locate an aquifer stratum with a low permeability stratum thereabove all -being below the earths surface, said aquifer stratum being a water `bearing stratum wherein when water is removed therefrom an underground water supply tends to replenish same to the original pressure, extending the bore hole to the lower portion of said aquifer stratum, and injecting gas into the upper portion of the aquifer stratum and selectively removing water from the lower portion of the aquifer stratum adjacent said bore hole at a rate corresponding to the flow of water in said stratum toward the bore .hole and the gas introduction to empty water from a gas storage volume in `said upper portion of the aquifer stratum to receive the injected gas.

2. The method of producing an underground storage space for gaseous substances under high pressure :comprising, exploring a desired area by known geological procedure including the formation .of a bore hole to locate strata bellow the earths surface wherein there is an aquifer strat-um with :a low permeability stratum thereabove, sinking a bore hole through said aquifer stratum, introducing .a casing into said bore hole with the lower end of said casing extending into the lower portion of said aquifer, sealing said casing in the stratum above the aquifer, providing a ow passage in said casing extending from the earths surface and communicating with the lower portion of said aquifer, providing a second flow passage in said casing extending from the earths surface and communieating with the upper portion of said aquifer, introducing gas under pressure down the second `flow passage and injecting same into the upper portion of the aquifer and slectively removing water from the lower portion of the aquifer through the first flow passage at a rate to empty water from a gas storage volume in said upper portion of the aquifer to receive the injected gas.

3. The method lof producing an underground storage space .for gaseous substances under high pressure comprising, exploring a desired area by known geological procedure including the formation of a bore hole to locate strata below the earths surface wherein there is an aquifer stratum with a -stratum adjacent and thereabove having a permeability of less than 0.001 millidarcy, said aquifer stratum having a porosity of 10 to 30 percent, sinking a bore hole through said aquifer stratum, introducing a easing into said -bore hole with the lower end of said casing extending to a suitable depth in said aquifer, sealing said casing in the stratum above the aquifer, running a tubing into said casing to a selected elevation adjacent the lower portion of said aquifer, providing a fluid seal relation between the tubing and the casing to close the lower end of an Iannulus therebetween, communicating said annulus with the upper portion of the aquifer, communicating the interior .of the tubing with the lower portion of the aqui-fer, introducing gas under pressure down the annulus of the casing and injecting same into the upper portion of the aquifer :and selectively removing water from the lower portion of the aquifer through the tubing for emptying water from a volume of the upper portion .of the aquifer yaround the casing to receive the gas.

4. A method of claim 3 wherein an interface of gas and water adjacent the casing is logged for suitable periods and the rate of gas injection and lproduction to and from the upper portion of the aquifer andthe rate of production and injection of water from and to the lower portion of the raquifer tare varied to maintain the interface of gas and water adjacent the casing in a down-cone.

S. The method of producing an underground storage space for gaseous substances under high pressure comprising, exploring a desired area by known geological procedure including the formation of a bore hole tolocate strata below the earths surface wherein there is an aquifer stratum with a stratum thereabove having a permeability of less than 0.001 millidarcy, said aquifer stratum having a porosity of l0 to 30 percent, sinking a -bore hole through said aquifer stratum, introducing a casing into said bore hole with the lower end of said casing extending to a suitable point relative the lower portion of said aquifer, sealing said casing in the stratum above the aquifer, running a tubing into said casing to a selec-ted elevation adjacent the lower portion of said aquifer, sproviding a fluid seal relation between the tubing and the casing and close the lower end of an annulus therebetween, communicating said annulus through a plurality of apertures adjacent the upper portion of the aquifer with said aquifer, communicating the interior of the tubing with the lower portion `of the aquifer, introducing gas under pressure down the :annulus of the casing and injecting same into the upper portion of the aquifer and selectively removing water from `the lower port-ion o'f the aquifer through the tubing for emptying water from a volume of the upper portion of the aquifer to receive the gas, and adjusting the relative rate of gas injection and production and water removal and injection to form a down-cone gaswater interface adjacent said casing.

6. The method .of utilizing an underground aquifer for storage of gaseous fluids comprising, providing a well which penetrates lower regions of an aquifer, providing in the well intermediate the height of the aquifer stratum a barrier completely separating zone-s o-f the well wit-h one zone having communication with the upper portion of the aquifer and the other zone having communication with the lower portion of the aquifer, providing a first flow channel between the surface of the ground and said `one zone of the 4bore hole, providing a second `flow channel separate from the first ow channel between the surface of the ground and the said other zone, introducing gas through the rst flow channel and said one zone to the upper portion of the aquifer and removing water from. the lower portion of the aquifer through the said other zone and second flow channel a-t a rate whereby a gas- Water interface adjacent the Well forms a down-cone.

7. A method of claim 6 wherein an interface of gas and water adjacent the well is logged for suitable periods and the rate of gas injection and production to and from the upper portion `of the aquifer and lthe rate of production and injection of water from and to the lower portion of the aquifer lare varied to maintain the interface of gas and water adjacent the well in a down-cone.

8. The method of utilizing an underground aquifer for storage lof gaseous fluids wherein said aquifer has a stratum thereabove of a permeability of les-s than 0.001 millidarcy, comprising, providing a well which penetrates lower regions of an aquifer, providing in the Well intermediate the height of the aquifer stratum a barrier completely separating zones of the well with one zone having communication with the upper portion of the aquifer and the other zone having communication with the lower portion o-f the aquifer, providing a rst flow channel between the surface of the ground and said one zone of the bore hole, providing a second flow channel separate from Ithe rst flow channel betwen the surface of the ground and the said other zone, introducing gas through the first flow channel Iand said -one zone to the upper |portion of the `aquifer yand `simultaneously removing water from the lower portion of the aquifer through the said other zone and second flow channel `at a rate greater than the rate of entry of water into the aquifer area surrounding the well whereby a gas-water interface ladjacent the well forms and maintains a down-cone.

9. The method of claim 8 wherein the aquifer has a porosity of l0 to 30 percent `and is at a level of at least five hundred feet below the surface of the earth and the gas and water introduction and removal are controlled to maintain a suitable differential press-ure relative to the native pressure of fluid in the aquifer.

10. An apparatus for use in the introduction and removal of gaseous substances in an underground storage in an aquifer having a stratum thereabove of low permeability comprising, a casing sealed in said stratum and extending through said aquifer, a tubing inside said casing and forming an annulus therebetween, said tubing and casing having inlet openings in the lower portions thereof and cooperating to provide communication of said tube with the lower portion of said aquifer adjacent said casing, a packer located in said casing adjacent to and above the tubing inlet to form a complete barrier between the tubing and the casing, said casing above said packer having openings therein fluidly communicating said casing annulus above the packer with the upper portion of the aquifer, means for flowing gas under pressure through said casing annulus above the packer to said aquifer to form a gas layer above a water layer in said aquifer adjacent said casing, means for removing gas from said aquifer through the casing annulus, means including flow control means associated with said tubing for removing and introducing water through said inlet openings from and into said aquifer adjacent the lower portion thereof whereby said gas displaces the water adjacent the casing and forms a gas storage volume surrounding said casing, said ow control means including a water level logging means for logging the gas-water interface adjacent the casing.

11. An apparatus for use in the introduction and removal of gaseous substances in an underground storage in an aquifer having a stratum thereabove with a permeability of less than 0.001 millidarcy, comprising, a casing sealed in said stratum and extending through said aquifer, a tubing inside said casing and forming an annulus therebetween said tubing having an inlet opening communicating with the lower portion of said aquifer adjacent said casing, a packer located in said casing adjacent to and above the tubing inlet to form a complete barrier between the tubing and the casing, said casing having a plurality of apertures below the packer communicating with the lower portion of the aquifer and a plurality of apertures above the packer communicating with the upper portion of the aquifer, means for flowing gas under pressure through said casing annulus and the apertures above the packer to said aquifer to form a gas layer above a water layer in said aquifer adjacent said casing, means for removing gas from said aquifer through the casing, and means including ow control means associated with said tubing for removing and introducing water from and into said aquifer adjacent the lower portion thereof in relation to the rate of introduction and removal of gas to maintain a gas storage volume in the upper portion of the aquifer adjacent the casing that has a gas-water interface in the form of an inverted cone surrounding said casing, said flow control means including a water level logging means for logging the gas-water interface adjacent the casing.

12. An apparatus as set forth in claim 11 wherein the means for flowing gas to the upper portion of the aquifer includes a gas pipe line and a compressor for taking gas from the pipe line and discharging said gas into the casing annulus under pressure for forcing water in the upper portion of the aquifer back from the casing.

13. An apparatus as set forth in claim 12 wherein the water removing means is `a mechanical pump in the casing and connected to said tubing.

14. An apparatus as set forth in claim 12 wherein the water removing means is a gas lift apparatus associated with said tubing and the discharge of the tubing is to a gas-water separator for removing the gas used by the gas lift from the water discharged from said tubing.

15. An apparatus as set forth in claim 14 wherein the separated water is dischraged to a reservoir and a pump means is associated with the reservoir to return water to the lower portion of the aquifer to maintain pressure therein.

16. The method of producing an underground storage space for gaseous substances under high pressure comprising, exploring a desired `area by known geological procedure including the formation of a bore hole to locate strata below the earths surface wherein there is an aquifer stratum with a low permeability stratum thereabove, sinking a bore hole through said aquifer stratum, introducing a casing into said bore hole with the lower end of said casing extending into the lower portion of said aquifer, sealing said casing in the stratum above the aquifer, providing a flow passage in said casing extending from the earths surface and communicating with the lower portion of said aquifer, providing a second flow passage in said casing extending from the earths surface and communicating with the upper portion of said aquifer, introducing gas under pressure down the second flow passage and injecting same into the upper portion of the aquifer and selectively removing water from the lower portion of the aquifer through ythe first ow passage to form a gas storage in said aquifer, suitably logging an interface of gas and water adjacent the casing, and varying the rate of gas injection to the upper portion of the aquifer and the rate of production of water from the lower portion of the aquifer to maintain the interface of gas and water adjacent the bore hole in a down-cone.

References Cited by the Examiner UNITED STATES PATENTS 2,524,933 10/ 1950 Silverman 166-42 X 2,811,205 10/1957 Spearow 166-45 X 2,936,030 5/ 1960 Allen 166-42 3,152,640 10/1964 Marx 166--9 3,175,614 3/1965 Wyllie 166-42 3,177,940 4/ 1965 Ten Brink 166-45 X CHARLES E. OCONNELL, Primary Examiner.

S, J. NOVOSAD, Assistant Examiner. 

1. THE METHOD FOR PRODUCING AN UNDERGROUND STORAGE SPACE FOR GASEOUS SUBSTANCES UNDER HIGH PRESSURE COMPRISING, EXPLORING A DESIRED AREA BY KNOWN GEOLOGICAL PROCEDURE, INCLUDING THE FORMATION OF A BORE HOLE TO LOCATE AN AQUIFER STRATUM WITH A LOW PERMEABILTY STRATUM THEREABOVE ALL BEING BELOW THE EARTH''S SURFACE, SAID AQUIFER STRATUM BEING A WATER BEARING STRATUM WHEREIN WHEN WATER IS REMOVED THEREFROM AN UNDERGROUND WATER SUPPLY TENDS TO REPLENISH SAME TO THE ORIGINAL PRESSURE, EXTENDING THE BORE HOLE TO THE LOWER PORTION OF SAID AQUIFER STRATUM, AND INJECTING GAS INTO THE UPPER PORTION OF THE AQUIFER STRATUM AND SELECTIVELY REMOVING WATER FROM THE LOWER PORTION OF THE AQUIFER STRATUM ADJACENT SAID BORE HOLE AT A RATE CORRESPONDING TO THE FLOW OF WATER IN SAID STRATUM TOWARD THE BORE HOLE AND THE GAS INTRODUCTION TO EMPTY WATER FROM A GAS STORAGE VOLUME IN SAID UPPER PORTION OF THE AQUIFER STRATUM TO RECEIVE THE INJECTED GAS.
 10. AN APPARATUS FOR USE IN THE INTRODUCTION AND REMOVAL OF GASEOUS SUBSTANCES IN AN UNDERGROUND STORAGE IN AN AQUIFER HAVING A STRATUM THEREABOVE OF LOW PERMEABILITY COMPRISING, A CASING SEALED IN SAID STRATUM AND EXTENDING THROUGH SAID AQUIFER, A TUBING INSIDE SAID CASING AND FORMING AN ANNULUS THEREBETWEEN, SAID TUBING AND CASING HAVING INLET OPENINGS IN THE LOWER PORTIONS THEREOF AND COOPERATING TO PROVIDE COMMUNICATION OF SAID TUBE WITH THE LOWER PORTION OF SAID AQUIFER ADJACENT SAID CASING, A PACKER LOCATED IN SAID CASING ADJACENT TO AND ABOVE THE TUBING INLET TO FORM A COMPLETE BARRIER BETWEEN THE TUBING AND THE CASING, SAID CASING ABOVE SAID PACKER HAVING OPENINGS THEREIN FLUIDLY COMMUNICATING SAID CASING ANNULUS ABOVE THE PACKER WITH THE UPPER PORTION OF THE AQUIFER, MEANS FOR FLOWING GAS UNDER PRESSURE THROUGH SAID CASING ANNULUS ABOVE THE PACKER TO SAID AQUIFER TO FORM A GAS LAYER ABOVE A WATER LAYER IN SAID AQUIFER ADJACENT SAID CASING, MEANS FOR REMOVING GAS FROM SAID AQUIFER THROUGH THE CASING ANNULUS, MEANS INCLUDING FLOW CONTROL MEANS ASSOCIATED WITH SAID TUBING FOR REMOVING AND INTRODUCING WATER THROUGH SAID INLET OPENINGS FROM AND INTO SAID AQUIFER ADJACENT THE LOWER PORTION THEREOF WHEREBY SAID GAS DISPLACES THE WATER ADJACENT THE CASING AND FORMS A GAS STORAGE VOLUME SURROUNDING SAID CASING, SAID FLOW CONTROL MEANS INCLUDING A WATER LEVEL LOGGINGMEANS FOR LOGGING THE GAS-WATER INTERFACE ADJACENT THE CASING. 